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| United States Patent |
5,338,789
|
|
Grosse-Puppendahl
, et al.
|
August 16, 1994
|
Fiber-reinforced polyphenylene ether molding compositions and process
for their preparation
Abstract
A fiber-reinforced molding composition, comprising:
a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of
30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by
weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene
and 0.1 to 2.5 parts by weight of an .alpha.,.beta.-unsaturated carboxylic
acid derivative or a precursor thereof;
b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces
bear functional groups which are capable of entering into chemical
coupling reactions with the .alpha.,.beta.-unsaturated carboxylic acid
derivatives; and optionally
c) dyes, pigments, plasticizers, flame retardant additives, processing
auxiliaries, other customary additives or combinations thereof.
| Inventors:
|
Grosse-Puppendahl; Thomas (Haltern, DE);
Baron; Christian (Haltern, DE);
Schmidt; Friedrich G. (Munster, DE)
|
| Assignee:
|
Huels Aktiengesellschaft (Marl, DE)
|
| Appl. No.:
|
865631 |
| Filed:
|
April 9, 1992 |
Foreign Application Priority Data
| Current U.S. Class: |
524/314; 523/213; 523/214; 523/215; 524/315; 524/321; 525/68; 525/92D; 525/133; 525/152 |
| Intern'l Class: |
C08K 005/11; C08K 005/29; C08K 003/40; C08K 003/04 |
| Field of Search: |
523/213,214,215,508
524/112,321,494,495,496,847,314,210,104,315
525/68,92,133,152
|
References Cited
U.S. Patent Documents
| 4131598 | Dec., 1978 | Abolins et al | 525/68.
|
| 4152316 | May., 1979 | Cooper et al. | 525/68.
|
| 4423189 | Dec., 1983 | Haaf | 525/92.
|
| 4614773 | Sep., 1986 | Sugio et al. | 525/68.
|
| 4647613 | Mar., 1987 | Jadamus et al. | 525/68.
|
| 4728693 | Mar., 1988 | Droscher et al. | 525/152.
|
| 4749737 | Jun., 1988 | van der Meer | 523/214.
|
| 4772664 | Sep., 1988 | Ueda et al. | 524/186.
|
| 4873276 | Oct., 1989 | Fujii et al. | 524/153.
|
| 4874810 | Oct., 1989 | Lee, Jr. et al. | 524/494.
|
| 4892900 | Jan., 1990 | Sasaki et al. | 525/133.
|
| 4900786 | Feb., 1990 | Abolins et al. | 525/68.
|
| 4929675 | May., 1990 | Abe et al. | 525/905.
|
| Foreign Patent Documents |
| 0357065 | Mar., 1990 | EP | 524/112.
|
Primary Examiner: Michl; Paul R.
Assistant Examiner: Szekely; Peter
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Parent Case Text
This application is a continuation of application Ser. No. 07/591,891,
filed on Oct. 2, 1990, now abandoned.
Claims
What is claimed as new and desired to be secured By Letters Patent of the
United States is:
1. A fiber-reinforced thermoplastic molding composition comprising as
ingredients:
a) 97 to 50% by weight, relative to the sum of (a) and (b), moldable
thermoplastic ingredients, the moldable thermoplastic ingredients in the
molding composition consisting of a mixture of 30 to 100 parts by weight
of a polyphenylene ether, 0 to 70 parts by weight of a styrene polymer
which is polystyrene, impact-modified polystyrene or styrene-butadiene
copolymer, 0 to 10 parts by weight of a polyoctenylene and 0.1 to 2.5
parts by weight of a compound of formula (I) or (II)
R.sub.1 --CO--CR.sup.2 .dbd.CR.sup.3 --CO--R.sup.4 (I)
R.sup.1 --CO--CR.sup.2 .dbd.CR.sup.3.sub.2 (I)
in which R.sup.1 and R.sup.4 are hydroxyl, aryloxy an/or alkoxy groups
having up to 12 carbon atoms or together are --O-- or --NR.sup.5 --,
R.sup.2 and R.sup.3 denote hydrogen or an alkyl or cycloalkyl group having
up to 12 carbon atoms, an alkyl group substituted by the radical
COR.sup.1, an aryl group, chlorine or together an alkylene group having up
to 12 carbon atoms, wherein R.sup.5 is hydrogen or an alkyl, aralkyl or
aryl group, each having up to 12 carbon atoms, a compound which under
conditions of mixing in the melt which may be formed during the
compounding of the ingredients of the thermoplastic molding composition is
converted to a compound of formula (I) or (II) by known reactions, or a
compound which is a copolymer of a compound of formula (I) or (II) with a
vinyl aromatic, and
b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces
bear functional groups which are capable of entering into chemical
coupling reactions with a compound of formula (I) or (II) or with said
copolymer of a compound of formula (I) or (II).
2. The fiber-reinforced thermoplastic molding composition of claim 1
containing a plasticizer.
3. The fiber-reinforced thermoplastic molding composition of claim 2
containing an antioxidant.
4. The fiber-reinforced thermoplastic molding composition of claim 2
containing a pigment.
5. The fiber-reinforced thermoplastic molding composition of claim 2
containing flame retardant.
6. The fiber-reinforced thermoplastic molding composition of claim 2
containing a copolymer of a compound of formula (I) with a vinyl aromatic.
7. The molding composition according to claim 1, wherein the polyphenylene
ether is a polyether based on 2,6-dimethylphenol.
8. The molding composition according to claim 1, wherein said composition
contains 1 to 10 parts by weight of a polyoctenylene.
9. The molding composition according to claim 1 wherein a compound of
formula (I) is present which is fumaric acid, maleic anhydride or
combinations thereof.
10. The molding composition according to claim 1, wherein the styrene
polymer is partly or completely composed of block copolymers of the A-B-A
type, where A denotes a polystyrene block and B denotes a polybutadiene
block which may be hydrogenated or unhydrogenated.
11. The molding composition according to claim 1, wherein the fibers
surfaces bear free amino, epoxide or isocyanate groups.
12. A process for the preparation of molding compositions according to
claim 1, wherein the individual components are mixed in a melt.
13. A molded object produced by the process according to claim 12.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fiber-reinforced molding compositions
having superior mechanical properties which are based on polyphenylene
ether resins, and also to a process for the preparation of these molding
compositions.
2. Description of The Background
Polyphenylene ethers (PPE), also known as polyphenylene oxides, are
polymers having a high heat resistance and also good mechanical and
electrical properties. As a rule, they are used as blends with polystyrene
resins, for example, DE-C-2,119,301 and 2,211,005 and/or polyoctenylene
(DE-A-3,442,273 and 3,518,277).
Many attempts have been made to increase the rigidity of PPE-containing
molding compositions by admixing reinforcing fibers composed of inorganic
or organic material in the resin. For instance, DE-A-2,364,901 discloses
polymer mixtures of PPE, polystyrene resins and glass fibers, the glass
fibers used in this case having a length of between 3.1 and 25.4 mm,
preferably of below 6.35 mm. EP-A-0,243,991 and the corresponding U.S.
Pat. No. 4,749,737 describe the mixing of very short, unsized fibers with
Si-H bond-containing siloxanes, to improve the fiber-matrix adhesion in
the composition, followed by mixing in the melt with PPE and a polystyrene
resin.
A specific modification of the fiber surface by treating the glass fibers
with vinylsilanes or gamma-glycidoxypropyl-trimethoxysilanes for use in
PPE-containing molding compositions is described in DE-A-2,132,595, JP
73/97,954, JP 74/10,826 and JP 85/88,072. DE-A-2,719,305 proposes the
opposite method, i.e. end-group modification of the PPE via a silylation
carried out before compounding. This technique however is a roundabout and
labor-intensive method of achieving an improved fiber-matrix coupling.
A commonly used surface modification of the reinforcing fibers is achieved
by treatment with aminoalkylsilanes, for example
gamma-aminopropyltriethoxysilane. Glass fibers which have been sized in
this manner are incorporated in numerous PPE-containing compositions, it
always being necessary to additionally modify the composition of the
thermoplastic matrix to bond the fibers to the matrix. For instance, JP
87/15,247 describes the addition of, for example, maleic
anhydride-modified polypropylene. JP 85/46,951 describes the addition of
ethylene-maleic anhydride copolymers and JP 85/44,535, DE-A-3,246,433 and
JP 82/168,938 describe the addition of styrene-maleic anhydride
copolymers. However, these polymeric additives have the disadvantage that
they reduce the heat resistance of the molding compositions or else they
are only partly compatible with the PPE matrix or in most cases are
incompatible and therefore impair the mechanical properties of the molding
compositions. A need continues to exist for a PPE based molding
composition of improved mechanical properties.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide
fiber-reinforced molding compositions based on PPE, which, while avoiding
the disadvantages described above, exhibit an improved adhesion between
fiber and matrix.
Briefly, this object and other objects of the present invention as
hereinafter will become more readily apparent can be attained by a molding
composition comprising
a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of
30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by
weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene
and 0.1 to 2.5 parts by weight of an .alpha.-.beta.-unsaturated carboxylic
acid derivative or a precursor thereof;
b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces
bear functional groups which are capable of entering into chemical
coupling reactions with .alpha.,.beta.-unsaturated carboxylic acid
derivatives; and optionally
c) dyes, pigments, plasticizers, flame retardant additives, processing
auxiliaries, other customary additives or combinations thereof.
DESCRIPTION OF THE DRAWINGS
A more complete understanding of the invention and many of the attendant
advantages thereof will be readily obtained as the same becomes better
understood by reference to the following detailed description when
considered in connection with the accompanying drawings, wherein:
FIG. 1 is a scanning electron micrograph of the fiber reinforced molding
composition of Comparative Example A; and
FIGS. 2a and 2b are scanning electron micrographs of the fiber reinforced
molding composition of Example 2 of the present invention, wherein FIG. 2b
is an enlargement of FIG. 2a.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The molding compositions of the invention can be processed to give molded
articles by the customary methods of thermoplastics processing, for
example injection molding or press molding. Suitable polyphenylene ethers
include primarily polyethers based on 2,6-dimethylphenol, the ether oxygen
of one unit being bonded to the benzene nucleus of the adjacent unit. In
principle, it is also possible to use other o,o'-dialkylphenols whose
alkyl radical preferably contains a maximum of 6 carbon atoms as long as
this radical does not have a tertiary carbon atom in the alpha position.
Furthermore, it is possible to use phenols which are substituted only in
one ortho-position by a tertiary alkyl radical, in particular a tertiary
butyl radical. Each of the monomeric phenols listed may be substituted by
a methyl group in the 3-position, and optionally also in the 5-position.
Obviously, it is also possible to use mixtures of the monomeric phenols
mentioned here.
The polyphenylene ethers may be prepared, for example, in the presence of
complex-forming agents such as copper bromide and morpholine, from the
phenols as disclosed in DE-A-3,224,692 and 3,224,691. The viscosity
numbers J, determined in accordance with DIN 53 728 in chloroform at
25.degree. C. are in the range of from 35 to 80 cm.sup.3 /g (concentration
5 g/l). Preference is given to the polymer of 2,6-dimethylphenol,
poly-(2,6-dimethyl-1,4-phenylene ether), having a viscosity number J from
45 to 70 cm.sup.3 /g. Normally, the polyphenylene ethers are used in the
form of powders or granules.
The polyoctenylenes are prepared by the ring-opening or ring-expanding
polymerization of cyclooctene (see, for example, A. Draxler,
Kautschuk+Gummi, Kunststoffe 1981, pages 185 to 190). Polyoctenylenes
having different proportions of cis- and trans-double bonds and also
different J-values and correspondingly different molecular weights are
obtainable by methods known in the literature. Preference is given to
polyoctenylenes having a viscosity number of from 50 to 350 cm.sup.3 /g,
preferably 80 to 160 cm.sup.3 /g, determined on a 0.1% strength solution
in toluene. 55 to 95%, preferably 75 to 85%, of their double bonds are in
the trans-configuration.
There are various methods of preparing a mixture of polyphenylene ether and
the polyoctenylene. One method is to dissolve the two polymers in a
suitable solvent and to isolate the mixture by evaporating off the solvent
or by precipitating it with a non-solvent. Another method is to combine
the two polymers in the melt. Further details are given in DE-A-3,518,277.
In a preferred embodiment, the molding composition contains 1 to 10 parts
by weight of polyoctenylene.
.alpha.,.beta.-Unsaturated carboxylic acid derivatives are understood to
mean, for example, compounds of the formulae (I) and (II):
R.sup.1 --CO--CR.sup.2 .dbd.CR.sup.3 --CO--R.sup.4 (I)
R.sup.1 --CO--CR.sup.2 .dbd.CR.sup.3.sub.2 (II)
in which
R.sup.1 and R.sup.4 are hydroxyl, aryloxy and/or alkoxy groups having up to
12 carbon atoms or together are --O-- or --NR.sup.5 --, R.sup.2 and
R.sup.3 denote hydrogen, an alkyl or cycloalkyl group having up to 12
carbon atoms, an alkyl group substituted by the radical COR.sup.1, an aryl
group, chlorine or together an alkylene group having up to 12 carbon
atoms, while R.sup.5 is hydrogen, alkyl, aralkyl or aryl groups, each
having up to 12 carbon atoms. Examples of these acids are maleic acid,
fumaric acid, itaconic acid, aconitic acid, tetrahydrophthalic acid,
methylmaleic acid, maleic anhydride, N-phenylmaleimide, diethyl fumarate
and butyl acrylate. In this selection, preference is given to the use of
fumaric acid and maleic anhydride. Obviously, it is also possible to use
mixtures.
It is also possible to use precursors of .alpha.,.beta.-unsaturated
carboxylic acid derivatives of this type which, under the conditions of
mixing in the melt, are converted to the said carboxylic acid derivatives
by known reactions such as, for example, elimination or reverse
Diels-Alder reaction.
Obviously, it is possible to add other compounds which promote the
incorporation of the .alpha.,.beta.-unsaturated carboxylic acid
derivatives, for example, by alternating copolymerization while grafting.
Suitable compounds in this category are primarily vinylaromatics such as,
for example, styrene, which enter into a reaction of this type in
particular with maleic anhydride. The preparation of graft copolymers of
this type is described in the German patent application DE-A-3,831,348.
The styrene polymer which is optionally added during the preparation or the
working-up of the polyphenylene ether should preferably be compatible with
the polyphenylene ether used. Its molecular weight Mw is in the range from
1,500 to 2,000,000, preferably in the range from 70,000 to 1,000,000.
Particularly preferred styrene polymers are polystyrene, impact-modified
polystyrene and also styrene-butadiene copolymers. Obviously, mixtures of
these polymers may also be used.
The styrene-butadiene copolymers may be random, tapered or block
copolymers. The toughness is increased by giving preference to the use of
block copolymers of the A-B-A type. The polystyrene blocks A have an
average molecular weight Mw of 4,000 to 150,000 and together make up to
33% by weight of the block copolymer. The polybutadiene block B, which may
also be hydrogenated or partly hydrogenated, has an average molecular
weight Mw of 20,000 to 480,000.
The reinforcing fiber present in the molding composition of the invention
bears on its surface preferably free amino, epoxide or isocyanate groups.
Amino groups are introduced, for example, by sizing with a copolyamide,
with low molecular weight amine compounds or specifically in the use of
glass fibers, with gamma-aminopropyltriethoxysilane; epoxide groups by
impregnation with uncrosslinked epoxy resins or, in the case of glass
fibers, with gamma-glycidoxypropyltrimethoxysilane; isocyanate groups by
sizing with a solution of uncrosslinked, preferably low molecular weight
polyurethane resins. The components III are preferably used to a maximum
amount of 30% by weight, relative to I.
The individual components may be mixed either simultaneously or in
succession. Generally, the unreinforced molding composition is initially
prepared in granule or melt form and to this is admixed the functionalized
fibers in a mixer having a good kneading action. This mixing may for
example be carried out using a single or twin-screw kneader or co-kneader.
Generally, the mixing temperature is between 250.degree. and 350.degree.
C., preferably between 260.degree. and 310.degree. C., and the residence
time is generally between 1 and 10 minutes, preferably between 3 and 5
minutes.
The molding compositions of the invention can be processed by customary
injection molding procedures under the same conditions as the
corresponding prior-art thermoplastic molding compositions. Even large
molded objects can be produced simply using the said molding compositions.
The molding compositions of the invention are used to produce moldings
which are subject to particular service stress (intermittent and/or
constant), a good fiber-matrix adhesion being of crucial importance in
these moldings. The molded objects are employed, for example, in the
construction of machines and apparatus for example for gear wheels or pump
components, in sporting equipment, in the motor vehicle industry or in the
electrical industry.
Having generally described this invention, a further understanding can be
obtained by reference to certain specific examples which are provided
herein for purposes of illustration only and are not intended to be
limiting unless otherwise specified.
Comparative Example A
100 parts by weight of polyphenylene ether having a J-value of 68 cm.sup.3
/g, which has been obtained by oxidative coupling of 2,6-dimethylphenol,
termination of the reaction and subsequent combined reaction/extraction in
accordance with DE-A-3,313,864 and 3,323,777 followed by evaporation of
the solvent and extruding the melt via a degassing extruder, are remelted
with 2 parts by weight of diphenylcresyl phosphate (DISFLAMOLL.RTM. DPK,
Bayer) and one part of the antioxidant IRGANOX.RTM. 1010 and also 15.6
parts by weight of an NH.sub.2 group-bearing carbon fiber (GRAFIL.RTM.
XAS/PA 6, Courtaulds Advanced Materials), which are metered into the PPE
melt in a twin-screw kneader at 280.degree. C. Before the product is
discharged, the volatile components are removed in a degassing zone. The
product is granulated, dried and injection molded to give test pieces. The
properties obtained from these are listed in Table 1. It can be seen
clearly from the scanning electron micrograph (SEM) that no adhesion
exists between fiber and matrix (low temperature fracture surface) (FIG.
1).
EXAMPLES 1 to 3
The experiment described in Comparative Example A is repeated but with the
addition of 0.5 to 1.5 parts by weight of maleic anhydride to the mixture
of PPE, diphenylcresyl phosphate and IRGANOX.RTM. 1010 and subsequent
metering of the carbon fiber into the melt. The constituents and
properties of the composition prepared in this way are listed in Table 1.
The scanning electron micrograph from Example 2 shows that an excellent
adhesion exists between fiber and matrix (low temperature fracture
surface) (FIGS. 2a and 2b).
COMPARATIVE EXAMPLE B
The experiment described in Comparative Example A is repeated but, instead
of the carbon fiber used in that example, an epoxy resin-sized carbon
fiber (TENAX.RTM. HTA-6-CN, Akzo (Enka AG) is used (Table 1).
EXAMPLE 4
The experiment described in Comparative Example B is repeated but, as
described in Examples 1 to 3, 1.5 parts of maleic anhydride are
additionally used (Table 1).
Obviously, numerous modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims, the invention may
be practiced otherwise than as specifically described herein.
TABLE 1
______________________________________
Example
A 1 2 3 B 4
______________________________________
PPE Parts by 100 100 100 100 100 100
weight
Diphenylcresyl
Parts by 2 2 2 2 2 2
phosphate weight
IRGANOX .RTM.
Parts by 1 1 1 1 1 1
1010 weight
Maleic Parts by -- 0.5 1 1.5 -- 1.5
anhydride weight
GRAFIL .RTM.
Parts by 15.6 15.6 15.6 15.6 -- --
XAS/PA 6 weight
TENAX .RTM.
Parts by -- -- -- -- 15.6 15.6
HTA-6-CN weight
Modulus of
MPa 8600 8400 9100 9200 7000 9500
elasticity in
tension
DIN 53 457
Tensile strength
MPa 98 117 132 122 92 136
DIN 53 455
Elongation at
% 1.5 1.8 1.9 2.2 1.9 1.8
break
DIN 53 455
Impact strength
kJ/m.sup.2
13 17 17 13 14 16
DIN 53 453
______________________________________
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